In the related art, JP 11-236696 A (Reference 1), JP 2008-291302 A (Reference 2), and JP 2006-336050 A (Reference 3) disclose various technologies for anodizing metallic material to be processed. Reference 1 discloses a technology for controlling a flow rate of electrolytic solution injected from a plurality of injection nozzles to a material to be processed so as to prevent heat burning of the material to be processed at the time of anodization. References 2 and 3 disclose a technology for injecting electrolytic solution toward an outer periphery of a material to be processed while rotating the cylindrical material to be processed so as to prevent heat burning of the material to be processed at the time of the anodization.
The technology disclosed in Reference 2 has a potential to suppress a surface temperature of the material to be processed to achieve enhancement of heat burning prevention in comparison with the technology disclosed in Reference 1 by rotating the material to be processed at the time of anodization. Specifically, however, in a case where the anodization is performed on the metallic material to be processed having a projecting portion on the surface thereof, a further technology which achieve uniformization of a thickness of an anodized film by suppressing a temperature rise of part of the surface of the material to be processed is required.